The present invention relates to optical subassemblies.
FIG. 1 illustrates an exemplary conventional optical subassembly. The device 100 comprises a glass slab 102, a plurality of filters 104a-104d coupled to the glass slab 102, an input/output port 106 optically coupled to the glass slab 102, and a plurality of ports 108a-108d, each optically coupled to a filter 104a-104d. Each filter 104a-104d transmits a particular wavelength or range of wavelengths, i.e., a channel, while reflecting the remaining channels. An optical fiber can be positioned at the ports 106 and 108a-108d. 
For example, as a demultiplexer, the input/output port 106 transmits a beam comprising channels xcex1-xcex4 through the glass slab 102 to the filter 104a. Filter 104a transmits xcex1 to port 108a and reflects xcex2-xcex4 through the glass slab 102 to filter 104b. Filter 104b transmits xcex2 to port 108b and reflects xcex3-xcex4 through the glass slab 102 to filter 104c. Filter 104c transmits xcex3 to port 108c and reflects xcex4 through the glass slab 102 to filter 104d. Filter 104d transmit xcex4 to port 108d. In this manner, the device 100 functions as a demultiplexer. As would be understood by one of ordinary skill in the art, the beam paths are approximately the same when the device 100 functions as a multiplexer except the channels are traveling in the opposite direction.
However, because the ports 108a and 108c are positioned at a different side of the device 100 than ports 106, 108b, and 108d, the device 100 can be difficult to fit onto a board. One or more of the optical fibers at the ports 106 and 108a-108d may need to be bent in order to accomplish the desired fit. This is especially difficult at the corners of the board.
Accordingly, there exists a need for a multiplexer/demultiplexer device with an improved port configuration. The improved port configuration should have all beams entering and exiting at the same side of the device, making the device easier to fit onto a board. The present invention addresses such a need.
The present invention provides an optical subassembly with an improved port configuration. The improved port configuration has all beams entering and exiting at the same side of the device.
In one aspect of the present invention, the device utilizes a core comprising a first and a second face, where the first and second faces are coupled, non-parallel, and non-co-planar for changing a path of a beam.
In another aspect of the present invention, filters are coupled to a third face of the core. An axis of the core is defined by the intersection of the first and second faces of the core. The light path traverses between the first or second face and each filter, such that, at each filter, no portion of the light path interferes with any other portion of the light path. In addition, the light path traverses the core in a direction along this axis.
In another aspect of the present invention, the device further comprises a common port and a plurality of ports residing at the same side of the device.
In another aspect of the present invention, the filters are optically coupled to the plurality of ports.
In another aspect of the present invention, the positions of the ports are adjustable to facilitate alignment.
In an exemplary embodiment, the positions of the ports are adjusted to facilitate alignment by first aligning the common port to a target at one of the plurality of ports, then aligning the plurality of ports to the common port.
In an exemplary embodiment, an optical device is provided, which comprises: a core, comprising a plurality of reflective faces; a plurality of filters, wherein each filter corresponds to one of a plurality of channels, wherein each filter is optically coupled to at least one of the plurality of reflective surfaces; a common port optically coupled to the core for transmitting a beam comprising the plurality of channels; and a plurality of ports, wherein each port is optically coupled to one of the plurality of filters, wherein each port transmits one of the plurality of channels, wherein the core and the plurality of filters multiplex the plurality of channels or demultiplex the beam, wherein the common port and the plurality of ports reside at a same side of the device.
In another exemplary embodiment, a multiplexing device is provided, which comprises: a core, comprising a plurality of reflective faces; a plurality of ports at a side of the device, wherein each port transmits one of a plurality of channels; a plurality of filters coupled to the core, wherein each filter corresponds to one of the plurality of channels, wherein each filter is optically coupled to the port that transmits its corresponding channel, wherein each of the plurality of filters transmits its corresponding channel to one of the plurality of reflective surfaces, wherein each channel is reflected to a common port such that the plurality of channels is multiplexed; and the common port at the side of the device, wherein the common port is optically coupled to the core for receiving the multiplexed plurality of channels.
In another exemplary embodiment, a demultiplexing device is provided, which comprises: a core, comprising a plurality of reflective faces; a common port optically coupled to the core at a side of the core for transmitting a beam comprising a plurality of channels to one of the plurality of reflective faces; a plurality of filters coupled to the core, wherein each filter corresponds to one of the plurality of channels, wherein each of the plurality of filters receives its corresponding channel from one of the plurality of reflective surfaces, wherein each filter transmits its corresponding channel and reflects any other channel; and a plurality of ports at the side of the device, wherein each port is optically coupled to one of the plurality of filters, wherein each port receives the corresponding channel transmitted by the filter.
Exemplary embodiments of the present invention may use one or more of the aspects described above, alone, or in combination.